Coil clamp



T. H. LONG COIL CLAMP April 26, 1932.

Filed Oct. 20, 1930 Thomaslilony ATTORNEY Patented Apr. 26, 1932 UNITEDSTATES PATENT OFFICE THOMAS H. LONG, 01 IRWIN, PENNSYLVANIA, ASSIGNOR'IO WESTINGHOUSE ELEC- TRIO & MANUFACTURING COMPANY, A CORPORATION OFPENNSYLVANIA COIL CLAMP Appllcatlon flled October 20, 1930. Serial No.489,852.

My invention relates to electric furnaces and particularly to electricinduct1on furnaces.

An object of my invention is to provide a relatively simple and highlyefficient clampmg and supporting mean'sfor the energizing coil of aninduction furnace.

In practicing my invention, I provide a pair of clamps located in closeoperative relation to the top and the bottom turns of an energizingcoil, a plurality of guide bars extending between the top and the bottomclamps, and a tension bar also extending therebetween, to permit ofdrawing the clamps toward each other. The clamps are made of metal, andthe tension and guide bars are made of electric-insulating material.

In thesingle sheet of drawings,

Figure 1 is a top plan View of a portion only of an energizing coil anda single clamping structure associated therewith,

Fig. 2 is a fragmentary view, in vertical section, through a coil andclamping structure embodying my invention,

Fig. 3 is a partial top plan view illustrating the supporting means;and,

Fig. 4 is a view, in side elevation, of the clamping structure shown inFig. 2, the view being taken on the line IVIV of Fig. 2.

The'clamping and coil-supporting structure, embodying my invention, isparticularly applicable for use with energizing coils cmbodied inrelatively large induction furnaces and has been designed withparticular reference to an energizing coil in which the diameter of theuppermost turns is greater than the diameter of the lower turns.

Referring to Figs. 1 and 2 of the drawings, I have illustratedanenergizing coil 11 as embodying a plurality of turns of a compositeconductor 12, which may be made of copper, and includes an inner solidcurrent-conducting portion 13 and an outer tubular portion 14, unitarywith the portion'13 and adapted to be traversed by a suitable coolingfluid. No terminal portions are shown, as these constitute no part of mypresent invention. Strips 16, of electricinsulating material and ofsubstantially annular shape, may be located between the several turns ofconductors 12 and may bemade of any suitable or desired material, suchas mica or its equivalent.

A plurality of clamping structures 17 are provided, one of which isshown in Figs. 1, 2 and 4, in clearer detail. Each clamping structureincludes an upper clamp 18 which is of substantially L-shape in lateralsection and has a plate portion 19 operatively engaging the uppersurface of the uppermost turn, and is preferably brazed to the conductor12 in order to provide a path therebetween of relatively high heatconductivity. Radially extending rib portions 21 are provided in orderto strengthen the clamp, and the lower portion of this clamp includestwo lugs 22 and 23 and across bar 24 extending therebet-ween. The lugs22 and 23 are hollow in order to receive two guide bars 26 and 27 of asuitable electric-insulating material, the upper ends of the guide barsbeing bolted to the hollow lugs 22 and 23 by bolts 28.

The lower clamp 29 of each clamping structure is made slightly greaterin radial dimension than is the upper clamp 18 but is otherwise ofsubstantially the same construction. Sockets 31 and 32 are provided inmember 29 and are spaced a suitable distance apart to receive thelowerends of guide bars 26 and 27. The guide bars 26 and 27 may be ofsubstantially rectangular shape in lateral section and may have thecorners, at the lower end, beveled, as indicated at 33, to avoid the useof sharp corners where the guide bars fit into the sockets 31 and 32.

A central portion 34 is provided, having a socket 36 therein to receivethe lower end of a tension bar 37, also of electric-insulating material,which extends upwardly between the guide bars 26 and 27. A metal yoke 38is bolted to the upper end of the tension member 37 by bolts 39, theupper end of which has a screw-threaded aperture therein for receivingthe tension bolt 41 which extends through cross bar 24 of the upperclamp. By turning the bolt 41, the lower clamp may be drawn upwardlytoward the upper clamp, the guide bars 26 and 27 maintaining the properrelation of the lower clamps 29 to the upper clamp 18 and alsosupporting the coil 12 radially thereof. It is obvious that the lowerportion of member 37 may also be made of metal, thus leaving only theintermediate portion of the member 37 to be made of electrio-insulatingmaterial.

The inner end portion 42 of lower clamp 29 is brazed to the outersurface of the lowermost turn of the energizing coil 12 in order to bein ood heat-conducting relation thereto. Ra ially extending ribs 43 areprovided on the lower clamp" member in order to strengthen the same.

Fig. 3 illustrates the method of supporting the energizing coil having aplurality of clamping structures associated therewith, as hereinbeforedescribed, in a metal tank 46. A plurality of lugs 47, eachof-substantially L shape, may have one portion welded or otherwisesecured to the inside of tank 46, at a suitable height, the other leg orportion being provided with a plurality of holes therethrough to receivea plurality of bolts 48 which extend through openings 49 in a portion ofthe members 37. By proper location of the lugs 47, the clam ingstructure may be secured thereto by the olts 48 to support the coilwithin the casing of the tank 46.

The clamping structure hereinbefore described provides a means fortightly clamping the turns of the energizing coil, the individual clampsbeing brazed or soldered to the end turns of the energizing coil so thatany heat, whether generated therein by electric inductive action orradiated or conducted thereto, may be, to a great extent, carried awayby the cooling fluid traversing the tubular portion of the conductor. Itis obvious that the clamp 18, particularly, is located in a position ofrelatively high temperature, and the cooling means provided for the coilwill be effective also to reduce the temperature rise in the clamps.

Since the electric-insulating material, comprising the parts 26, 27 and37, will not, in general, be such as will be able to withstand therelatively high temperatures existing at the top of the coil, a heatscreen is provided between the material being heated or heattreated andthe said parts. By heat screen, I refer to the set of tubular portions14 of the coil 11 which are traversed by a cooling fluid and which will,therefore, reduce greatly the transmission of heat from the heatedmaterial within the coil 11 to the parts 26, 27 and 37. In order toinsulate the coil 11 from yoke 38, I provide a layer 51 of electric andheatinsulating material, such as mica or a high grade of asbestos,betweenthe outer faces of the tubular portions 14 and the member 38 andextend this along the entire axial length of the coil.

The device embodying my invention thus provides a relatively simpleclamping structure in which its members which are subjected to hightemperatures are fluid cooled, these members being connected byelectric-insulating parts of suitable shape, one of which is availableto support the entire coil structure in a metal tank or casing.

Since various modifications may be made in the device embodyin myinvention without departing from the spirit and' scope thereof, I desirethat only such limitations shall be placed thereon as are imposed by theprior art or are set forth in the appended claims.

I claim as my invention:

1. In an electric furnace having an energizing coil, a coil-clampingstructure including top and bottom clamps, a guide bar opera tivelyengaging the outer surface of thecoil to support the same and extendingbetween the clamps to hold the clamps in alined positions at the ends ofthe coil, and means for drawing the clamps toward each other.

2. In an electric furnace having an energizing coil, a coil-clampingstructure including top and bottom clamps, a guide bar having one endsecured to one clamp and having its other end slidable in the otherclamp, and means secured to the two clamps for drawing them toward eachother. 3. In an electric furnace having an energizlng coil and anenclosing casing, a coil-clamping-and-supporting structure including topand bottom clamps, guide bars, each having one end secured to one clampand the other end slidable in the other clamp, an adjustable tension barconnecting the two clamps to draw them toward each other, and means onsaid tension bar to cooperate with the casing to support the coiltherefrom.

4. In an electric furnace having an enclosin casing and an energizingcoil therein, a co1l-clamping-and-supporting structure in cluding clampsat each end of the coil, guide bars extending between the clamps, eachguide bar having one end rigidly secured to one clamp and its other endslidable in the other clamp, an adjustable tension member having itsends connected to the clamps to effect compression of the coil thereby,and means on the casing cooperating with the tension member to supportthe coil.

5. In an electric induction heater, a coil having a plurality of turnsof a fluid-cooled conductor, a coil-clamping structure including top andbottom clamps in intimate heatexchanglng relation to the respective endturns of the coil, bars of electric-insulating material extendingbetween the clamps and providing a radial support for the coil.

6. In an electric induction heater, a coil having a plurality of turnsof a fluid-cooled conductor, a coil-clamping structure including top andbottom clamps in intimate heat exchanging relation to the respective endturns of the coil, and an adjustable'tension device operativelyassociated with the clamps for1 drawing them together to compress thecol 7.. In an electric induction heater having a plural-turn energizingcoil, a coil-clamping structure including metal top and bottom clamps,means for securing said clamps in intimate mechanical relation to thetop and to the bottom turn of said coil, and means closely andoperatively j associated with at least the top and the bottom turns ofthe coil for effecting cooling of the clamps and of the end turns of thecoil.

8. An electric-induction heater having an energizing coil and acoil-clamping structure including a fluid-cooled clamp at one end of thecoil.

9. In an electric induction furnace having 'a plural-turn energizingcoil, a coil-clamping structure including top and bottom clamps engagingthe respective end turns of the coil,

adjustable tension means between the clamps to draw the same together,electric-insulating means operatively associated with the adjustabletension-means, and fluid-coolin means closely operatively associatedwith t e energizing-coil for reducing the temperature of theelectric-insulating means.

10. In an electric induction heater having a plural-turn energizingcoil, :1. coil-clampi'ng-and-supporting structure including a pluralityof pairs of clam s located, respectively, at opposite ends of t e coil,a plurality I of bars of electric-insulating material extending betweenthe clamps of each pair, and

means on one of said bars for attaching said coil to a suitable supportIn testimony whereof, I have hereunto subscribed my name this .first dayof October,

. 'IHOMAS H. LONG.

